Endoscopy in the medical field allows internal features of the body of a patient to be viewed without the use of traditional, fully-invasive surgery. Endoscopic imaging systems enable a user to view a surgical site and endoscopic cutting tools enable non-invasive surgery at the site. For instance, an RF generator provides energy to a distal end tip of an RF probe within the surgical site. In one mode, the RF probe provides RF energy at a power level to ablate or otherwise surgically remove tissue. In another instance, RF energy is provided to the RF probe in order to coagulate the tissue at the surgical site to minimize bleeding thereat.
Tissue ablation is achieved when a high power electrical signal having a sufficiently large voltage is generated by a control console and directed to an attached probe. Application of the high power signal to the probe results in a large voltage difference between the two electrodes located at the tip of the probe (presuming a bipolar probe), with the active electrode being generally 200 volts more than the passive or return electrode. This large voltage difference leads to the formation of an ionized region between the two electrodes, establishing a high energy field at the tip of the probe. Applying the tip of the probe to organic tissue leads to a rapid rise in the internal temperature of the cells making up the neighboring tissue. This rapid rise in temperature near instantaneously causes the intracellular water to boil and the cells to burst and vaporize, a process otherwise known as tissue ablation. An electrosurgical “cut” is thus made by the path of disrupted cells that are ablated by the extremely hot, high energy ionized region maintained at the tip of the probe. An added benefit of electrosurgical cuts is that they cause relatively little bleeding, which is the result of dissipation of heat to the tissue at the margins of the cut that produces a zone of coagulation along the cut edge.
In contrast to tissue ablation, the application of a low power electrical signal having a relatively low voltage to the active electrode located at the tip of the probe results in coagulation. Specifically, the lower voltage difference established between the active and return electrodes results in a relatively slow heating of the cells, which in turn causes desiccation or dehydration of the tissue without causing the cells to burst.
FIG. 1 corresponds to FIG. 1 of U.S. Patent Publication No. 2007/0167941, owned by the same assignee hereof, the disclosure of which is hereby incorporated by reference.
As illustrated in FIG. 1, a typical electrosurgical system 10 includes an electrosurgical probe 12 (hereafter referred to simply as “probe”) and a control console or controller 14. Interface 15 enables configuration of various devices connected to the console 14. The probe 12 generally comprises an elongated shaft 16 with a handle or body 18 at one end and a tip 20 at the opposite end. A single active electrode 19 is provided at the tip 20 if the probe 12 is of a “monopolar” design. Conversely, the probe 12 may be provided with both an active electrode 19 and a return electrode 21 at the tip 20 if the probe is “bipolar” in design. The probe 12 connects to control console 14 by means of a detachable cable 22. The current for energizing the probe 12 comes from control console 14. When actuated, the control console 14 generates a power signal suitable for applying across the electrode(s) located at the tip 20 of the probe 12. Specifically, current generated by the control console 14 travels through the cable 22 and down the shaft 16 to tip 20, where the current subsequently energizes the active electrode 19. If the probe 12 is monopolar, the current will depart from tip 20 and travel through the patient's body to a remote return electrode, such as a grounding pad. If the probe 12 is bipolar, the current will primarily pass from the active electrode 19 located at tip 20 to the return electrode 21, also located at tip 20, and subsequently along a return path back up the shaft 16 and through the detachable cable 22 to the control console 14.
After configuration of the control console 14 is carried out by means of the interface 15, actuation and control of the probe 12 by the surgeon is accomplished by one or more switches 23, typically located on the probe 12. One or more remote controllers, such as, for example, a footswitch 24 having additional switches 25-28, respectively, may also be utilized to provide the surgeon with greater control over the system 10. In response to the surgeon's manipulation of the various switches 23 on the probe 12 and/or remote footswitch 24, the control console 14 generates and applies various low and high power signals to electrode 19.
Actuation of coagulation switch 26 of footswitch 24 results in coagulation of the tissue adjacent the tip 20 of the probe 12. While operating in coagulation mode, the control console 14 of the prior art system shown in FIG. 1 is configured to drive the electrosurgical probe at a low, but constant, power level. Due to inherent varying conditions in tissue (i.e., the presence of connective tissue versus fatty tissue, as well as the presence or absence of saline solution), the impedance or load that the system experiences may vary. According to Ohm's law, a change in impedance will result in a change in current levels and/or a change in voltage levels, which in turn, will result in changing power levels. If the operating power level of the system changes by more than a predefined amount, the control console 14 will attempt to compensate and return the power back to its originally designated level by regulating either the voltage and/or current of the power signal being generated by the console and used to drive the attached probe 12.
Electrosurgical systems 10 also have a cutting mode for cutting tissue. Actuation of cutting switch 25 of the footswitch 24 places the electrosurgical system 10 in the cutting or ablation mode by application of a high energy signal to probe 12. In the cutting mode, the controller 14 outputs constant energy to the electrosurgical probe 12 while an operator maintains at least a predetermined force to actuate the cutting switch 25.
In a cutting operation, to change the power level of energy applied to the electrosurgical probe 12, the cutting switch 25 must be off. Then a user actuates either of switches 27, 28 on the footswitch 24, which function as controls for increasing and decreasing the power intensity output level, respectively. The electrosurgical system 10 senses actuation of increase switch 27 for increasing the power intensity value for output by the control console 14 depending on the original intensity value setting and the number of times the switch 27 is pressed. Likewise the electrosurgical system senses actuation of decrease switch 28 for decreasing the power intensity value from a previous value. Then, upon actuation of switch 25, the RF generator in the console 14 applies power to the probe 12 at the newly selected power level.
While the system shown in FIG. 1 adjusts cutting energy that is output from an RF generator in the control console 14, the changes in power level are made while the RF generator is off. Thus, a cutting operation must be interrupted or discontinued to change the power level. FIG. 2 shows one example wherein eleven separate discrete power levels are selectable for an electrosurgical system. Turning off energy to the electrode 19 to change power levels increases the length of time required to perform a surgery, which can be detrimental to the patient.
In the electrosurgical system 10 shown in FIG. 1, a non-volatile memory device (not shown) and reader/writer (not shown) can be incorporated into the handle 18 of the electrosurgical probe 12, or alternatively, incorporated into or on the cable 22 that is part of the probe 12 and which is used to connect the probe 12 to the control console 14 of the system. Alternatively, the memory device may be configured so as to be incorporated into or on the communication port that is located at the free end of the cable 22 and which is used to interface the cable with a corresponding port on the control console 14.
During manufacturing of the probe shown in FIG. 1, data representing probe-specific operating parameters is loaded into the memory device. Upon connection of the probe 12 to the control console 14 of the electrosurgical system 10, the data stored in the probe's non-volatile memory can be accessed by a reader and forwarded on to the control console 14. As such, once an electrosurgical probe 12 is connected, the control console 14 accesses the configuration data of the specific probe 12 and automatically configures itself based on the operating parameters of the probe.
Beyond probe-specific operating parameters, the memory device within each attachable probe 12 can store additional data concerning usage of the probe. This usage data includes a variety of information. For example, usage data may represent the number of times an electrosurgical probe 12 has been used, or the duration of the time that the probe has been activated overall or operated at different power levels. Additional usage data may restrict the amount of time that a specific attachable probe can be used. In addition to usage data, the prior art memory device can store information concerning any errors that were encountered during use of the probe 12.
One embodiment of the invention is directed to a system for an electrosurgical probe that dynamically adjusts power output from the probe without deactivating and then reactivating an RF generator. This arrangement can minimize the length of time for an operating procedure.
One embodiment of the invention disclosed herein is directed to improving cutting of tissue by an electrosurgical probe, such as by manually adjusting or varying the intensity of power delivered to tissue by a generator without temporarily interrupting the application of power. This arrangement also includes an actuator for coagulating tissue at a constant power level.
In another embodiment of the invention, operation of an electrosurgical system is obtained by providing a controller to vary the intensity of power applied to an electrosurgical probe without disruption in a first variable mode, and by providing a second fixed mode wherein energy to the RF probe is discontinued to allow a user to change the power level.